Catalytic treatment of naphthas



Jan. '16, 1945. r v .1. c, MUNDAY' ET AL CATALYTIC TREATMENT OF NAPHTHAS Filed Nov; 9,1940 2.

Sheefs-Sheet 1 PRODUCT :2 PRODUCT Patented Jan. 16, 1945 UNITED STATES PATENT OFFICE 2,367,365 CATALYTIC TREATMENT OF NAPHTHAS John C. Munday, Cranford, N. J., and Eldon E. Stahly, East Baton Rouge, La., assignors to Standard Oil Develo ration of Delaware pment Company, a corpo- Application November 9, 1940, Serial No. 364,970

8 Claims. (Cl. 196-53) ess in which hydrocarbon oils consisting essentially of hydrocarbons boiling in the gasoline range are subjected to treatment at a temper'ature in excess of 500 F. in the presence of catalysts and in the presence of substantial quantities of added or recirculated hydrogen to produce a dehydrogenated or otherwise chemically reconstructed product, for example of anti-knock characteristics superior to those of the starting material, with or without an accompanying change in molecular weight, the said treatment being carried out under such conditions that there is a net production of free hydrogen therein. By the term chemically reconstructed is meant something more than the mere removal of impurities or ordinary finishing treatments. The reactions which occur in the catalytic reforming treatment are principally dehydrogena-' tion and aromatization but other reactions such as desulfurization, alkylation and isomerization may also occur to a greater or lesser extent depending upon the particular conditions of operation used. 1

The terms hydrofining or catalytic hydrofining wherever used in the specification and claims shall be understood to mean any process of treating hydrocarbon oils consisting essentially of hydrocarbons boiling in the gasoline range at a temperature below that at which substantial pyrolysis or decomposition occurs in the presence of catalysts and in the presence of substantial quantities of hydrogen to efiect a partial saturation and refining of the hydrocarbon oil and to accomplish essentially the same re u lts as would be obtained by the conventional methods of finishing such as by treatment/with sulfuric acid and caustic and water washing.

A typical process o'fcatalytic reforming in the presenceflofhydrogen is one in which a naphtha is subjected to treatment at a temperature'between 850 and 1050 F., under a pressure between slightly above atmospheric and about 750 pounds per square inch, in the presence of a catalyst which promotes reforming and is capable of being regenerated when its activity has been substantially diminished, and in the presence of between 500 and 5000 cubic feet of gas per barrel of oil,

said gas containing between 20 and 90 mol percent of free hydrogen. The rate at which the naphtha is passed through the catalyst mass may vary between 0.2 and 5.0 volumes of liquid naphtha per volume of catalyst per hour. The various conditions of operation are adjusted within these limits vis-a-vis one another so that /anet production of free hydrogen will result in th treatment. The importance of this net production of free hydrogen will be more apparent as the description of the invention proceeds.

Characteristic of processes of this type is the fact that the catalyst gradually loses its activity in promoting the desired reactions due, it is believed, to the formation or deposition thereon during the reaction of carbonaceous contaminants such as coke. The rate of coke deposition is appreciably retarded by the fact that the reaction is conducted in the presence of hydrogen but nevertheless after periods of 6 to 12 hours or more, the activity of the catalyst has been reduced to such an extent that it is economically necessary to regenerate its activity. This may be done by passing hot, inert gases containing regulated quantities of air or oxygen through the catalyst mass until substantially all the carbonaceous material has been burned out. Prior to the passage of the hot, oxygen-containing gasesthrough the catalyst mass, it is desirable to purge the catalyst of all traces of oil or hydrogen by blowing out the catalyst chamber with steam or other inert gas such as nitrogen, flue gas, carbon dioxide, etc. This purging operation is also desirable after th regeneration treatment to remove traces of oxygen. Following regeneration and purging, the fiow of oil and hydrogen through the catalyst may be resumed and thereafter alternate reaction and regenerationcycles may be carried out an indefinite number of times.

A typicalcatalytic hydrofining process is one in which a naphtha is subjected to treatment at temperatures from 500 to 800 F. or higher, under pressures from slightly above atmospheric to 750 or more pounds per square inch, in the presence of a catalyst which promotes hydrogenation and in the presence of substantial quantities of hydrogen. The rate at which the naphtha may be passed through the catalyst s ordinarily higher than the permissible rate in catalytic reforming and may be between say 0.2 a nd 5 vo1umes of naphtha per-volume gfcatalyst per hour. Under certain conditions, as for example, when operating in the higher pressure range, the temperature may be considerably higher tlian 800 F., say about"900"F;"or'even higher.

The type of catalyst it is preferred to use in catalytic reforming in the presence of hydrogen comprises aluminum oxide in any of its various forms together with from 1 to 50 per cent by weight of oxides or sulfides of metals of the II, IV, V, VI and VIII groups of the periodic system. Oxides or sulfides of chromium, molybdenum, tungsten, vanadium, cobalt and nickel are especially good. Catalysts of this type can be regenerated an indefinite number of times by the method referred to above.

It has been observed that as these catalysts become less and'less activein promoting dehydrogenation and other reforming reactions, they become more and more active in promoting hydrogenation. This is evidenced by the fact that as a reforming cycle proceeds the net production of free hydrogen decreases, indicating that the net consumption of hydrogen is increasing. It has also been observed that when the catalyst has become so inactive that it is no longer useful for promoting reforming reactions, it is still sufficiently active to promote hydrogenation.

From the foregoing description it will be apparent that the time the catalyst is being regenerated represents a direct loss of capacity of the catalyst insofar as the production of reformed hydrocarbon oil is concerned.

It is a principal object; of the present invention therefore to provide a process in which the catalyst after being used in a catalytic reforming cycle until it requires regeneration is used for catalytic hydrofining prior to the regeneration. In this way the length of time the catalyst can be used for a useful purpose before being regenerated is greatly prolonged. At the same time, by effecting a catalytic hydrofining of the reformed hydrocarbon oil in the presence of the deactivated reforming catalyst it is not necessary subsequently to subject the reformed oil to a separate finishing treatment.

It is also an object of the present invention to provide a continuous method for catalytic reforming in the presence of hydrogen and catalytic hydrofining notwithstanding that the catalyst requires periodic regeneration.

It is a further object of the present invention to provide a process of catalytic reforming in the presence of hydrogen and catalytic hydrofining of the reformed product in which the same cata iyst is used to premote both reactions.

The nature of the process and the manner in which it may be carried out will be fully understood from the following description when read with reference to the accompanying drawings of which Fig. 1 illustrates diagrammatically the lines of flow when three reaction zones are used and when one reaction zone is idle for a portion of the time; and

Fig. 2 illustrates diagrammatically the lines of flow when four reaction zones are used and the operation is continuous.

Referring to Fig. 1, letters A, B and C designate the three different successive hook-ups which are possible when three reaction zones are used. Numerals l, 2 and 3 designate the three reaction zones respectively. Referring to the hoolrup designated A, it will be assumed that reaction zone i contains fresh or freshly regenerated catalyst, that reaction zone 2 contains cataing operation.

lyst which has already been used for catalytic reforming in the presence of hydrogen and has become too inactive for further use for this purpose, and that reaction zone 3 contains catalyst which has already been used both for catalytic reforming in the presence of hydrogen and for catalytic hydrofining and is now ready for regeneration. Fresh feed is introduced into reaction zone I through line 4 and in this reaction zone is subjected to catalytic reforming in the presence of hydrogen under conditions such that there will be a net production of free hydrogen. The products of reaction leave reaction zone I through line 5 andare introduced directly into reaction zone 2 wherein they are subjected to catalytic hydrofining. Here the importance of the net production of free hydrogen in the catalytic reforming step becomes apparent because this net production of free hydrogen provides the additional hydrogen necessary for the hydrofin- In most cases it isunnecessary to add hydrogen from an extraneous source to the hydrofining operation but it should be under stood that this may be done when certain feed stocks, for example those of low hydrogen content are used. and in certain circumstances as for example where the net production of free hydrogen in the catalytic reforming operation falls off unexpectedly due to disturbances in operation.

The products of the hydrofining in reaction zone 2 are removed through line 6. The unused hydrogen-containing gas is separated from the liquid products which are then subjected to the usual fractionation and finishing treatments as will be understood. The hydrogen-containing gas is recirculated to the reforming step.

While these operations are going on in reaction zones l and 2, the catalyst in reaction zone 3 is being regenerated. Numeral l designates the line through which the regenerating gases are introduced into reaction zone 3 and numeral 8 desi nates the line through which the waste gases are removed. Ordinarily the length of time requ red to regenerate the catalyst will be less than that in which the catalyst in reaction zone l can be used for reforming so that after regeneration.

reaction zone 3 may stand idle for a time until the reaction zone I is switched to hydrofining.

When the catalyst in reaction zone I has lost activity to such an extent that it is no longer expedient to continue it on reforming (this point is ordinarily indicated by the fact that the net production of free hydrogen falls below a previously determined satisfactory level), the hookup of the three reaction zones is changed to that shown in B.

Referring to B, like numerals are used to desig nate corresponding lines in A. For example, the feed is now introduced into reaction zone 3 in which reforming takes place, the products from reaction zone 3 pass into reaction zone i where the catalyst already spent for reforming in A is still capable of effecting hydrofining, and the catalyst in reaction zone 2 is regenerated.

When it is no longer expedient to continue reforming in reaction zone 3 the hook-up is changed to that shown in C where again like numerals are used to designate corresponding lines in A and B. In C the feed is introduced into reaction zone 2 which now contains freshly regenerated catalyst and the products from reaction zone 2 pass through reaction zone 3 which now contains catalyst already spent for reforming but still capable of effective hydrofining. The catalyst in reaction zone I is now regenerated..

Operation according to that shown in C is continued until the catalyst in reaction zone 2 is no longersufliciently active for reforming and the hook-up is then switched to that shown in-A, previously described, and the same cycle is repeated again an indefinite number of times until the catalyst in one or more reaction zones requires replacement.

Referring to Fig. 2, letters D, E, F and G designate four different successive hook-ups which are possible when four reaction zones are used. This operationhas the advantage over the three reaction zone operation illustrated in Fig. 1 in that it makes continuous operation in all reaction zones possible. Two reaction zones are always on reforming while the third is on hydrofining and the fourth on regeneration.

Referring to the hook-up designated by the letter D, numerals II), II, I2 and I3 designate the four reaction zones respectively. Fresh feed is introduced into reaction zone I through line I I which is maintained under reforming conditions. The products from reaction zone I0 pass through lines I5 and I6 into reaction zone II which' ismaintained under hydrofining conditions and contains catalyst which has already been used for reforming. Fresh feed is also introduced through line H into reaction zone I2 which is also maintained under reforming conditions and contains catalyst which has been used for reforming for a longer period than that in reaction zone I0. The products from reaction zone I2 pass through lines I8 and I6 into reaction zone II.

Thus the products of reforming from both reaction zones I0 and I2 pass through reaction zone II for hydrofining. As pointed out above, the space velocity in hydrofining may be substantially higher than that in reforming so that a single reaction zone maintained under hydrofining conditions may take care of the reformed products from two reaction zones simultaneously. The hydrofined products leave reaction zone II through line I9 and are separated into normally gaseous and normally liquid products in the usual way and the normally gaseous products which are rich in hydrogen are recycled to the two reforming zones. While these operations are going on in reaction zones III, II and I2, the catalyst in reaction zone I3 which has already been used for reforming and hydrofining is being regenerated. The regenerating ases are introduced into reaction zone I3 through line and the waste gases are removed through line ZI.

By the time the catalyst in reaction zone I3 has been regenerated the catalyst in reaction zone "I2 will have become too inactive for further efficient reforming so the hook-up is changed to that shown in E. Fresh feed is continued to be introduced into reaction zone Ill and is now also introduced into reaction zone I3 which contains freshly regenerated catalyst. The products from both reaction zones I0 and I3 are introduced into .reaction zone I2 for hydrofining and the catalyst pass through reaction zone III for hydrofining and the catalyst in reaction zone I2 is regenerated.

Again when the catalyst in reaction zone I3 has become too inactive for further reforming the hook-up is changed to that shown in G. Fresh feed is continued to be introduced into reaction zone II and is now also introduced into reaction zone I2 which contains freshly regenerated catalyst. The reformed products from reaction zones II and I2 arepassed through reaction zone I3 which is now maintained under hydrofining conditions. The catalyst in reaction zone III meanwhile is regenerated.

When the catalyst in reaction zone II has become too inactive for further reforming, the hookup is changed again to that shown in D and thereafter the same cycle of hook-ups is repeated indefinitely until the catalyst in one or more of the' reaction zones requires replacement.

In the drawings the various successive hookups of the apparatus have, for the sake of clarity and ease in description, been illustrated separately. It should be understood however that all of the various hook-ups may be accomplished in one set of reaction vessels with appropriate piping and arrangement of valves, tanks and pumps.

In the operation of the process, the usual conditions for catalytic reforming in the presence of hydrogen and for catalytic hydrofining may be used. It is preferable to operate the catalytic reforming under conditions such that there will be a net production of free hydrogen at least sufficient to compensate for the hydrogen which is consumed in the hydrofining operation so that there will be no overall netconsumption of free hydrogen. The amount of the net hydrogen produced in the catalytic reformin operation may be regulated in several ways. If it is desired to increase the net production of hydrogen, the total pressure may be lowered, the temperature may be raised or the proportion of lower boiling hydrocarbons in the feed may be increased. It will be understood that at the beginning of a reforming cycle when the catalyst is-either fresh or freshly regenerated, the net production of free hydrogen is ordinarily at a maximum for a given set of operation conditions so that expedients for increasing the net production of free hydrogen need ordinarily only be resorted to near the end of a reforming cycle when the net production of hydrogen normally tends to fall off as the catalyst loses its reforming activity.

The type of catalyst used in the process may be any of those mentioned above which are capable of being regenerated. It is preferred to use mixtures of aluminum oxide and chromium oxide or aluminum oxide and molybdenum oxide in .which the chromium and molybdenum oxides constitute from 1 to 50% by weight of the mixtures.

The method of regeneration may be the same as that described above or any other suitable method but this in itself forms no part of the present invention.

In the foregoing description of the invention it has been assumed that the products obtainedis especially advantageous.

such cases it will be understood that the catalytic hydrofining capacity of the catalyst which has become spent in the catalytic reforming operation need not be wasted but may be made use of to treat materials other than the products of the catalytic reforming operation. For example, highly unsaturated naphthas such as cracked naphthas may be passed over the catalyst, prior to regeneration in order either to refine such naphthas or to prepare them for a subsequent catalytic reforming treatment. Similarly a naphtha obtained from any other source or process which requires only a finishing treatment may be given this finishing treatment by bein passed over the catalyst prior to regeneration. It will be understood, of course, that the hydrogen-containing gases will be separated from the prodnets of the catalytic reforming in the presence of hydrogen and that these gases will be used for the catalytic hydrofining of the other material.

The foregoing description and the drawings also illustrate a type of operation in which a fixed or stationary catalyst is used. It should be understood, however, that the operation may 'be carried out with equally satisfactor results when the catalyst is used in finely divided or powdered form suspended in the mixture of oil vapors and hydrogen. Suitable means, such as cyclone separators, for separating the powdered catalyst from the reaction products will of course be required for this type of operation, but except for the mechanical change made necessary by the use of powdered catalyst, th operating conditions may be essentially the same as those used in operation with stationary catalysts.

One type of operation with powdered catalyst This is the type of operation in which what may be called a fluid catalyst is used. By the term fluid catalyst is meant that the mixture of oil vapors, hydrogen and powdered solid catalyst behaves in much the same way as a liquid and is subject to the same laws with respect to density, static head and the like as a liquid. In fluid catalyst operation the ratio of powdered solid catalyst to gases is relatively high and the length of time the catalyst remains in the reaction zone may be substantially longer than the length of time the oil vapors and hydrogen remain therein. Th velocity of the catalyst through the reaction zone is therefore less than could be the case in an ordinary powdered catalyst system where the powdered solid material is carried along at the same velocity as the vapors and hydrogen. The use of powdered catalyst in any form has one important advantage over the use of fixed or stationary catalyst in the present process in that it eliminates the necessity for excessive manipulation of valves and the frequent switching of the fiow of material from one reaction vessel to another.

We claim:

1. An improved method for preparing a finished motor fuel of high octane number which comprises subjecting a hydrocarbon oil consisting essentially of hydrocarbons boiling in the gasoline range to catalytic reforming in the presence of hydrogen under conditions such that there is a substantial net production of free hydrogen in the reaction in the presence of a catalyst which gradually loses its reforming activity but is capable of being regenerated, then subjecting the products of this treatment to catalytic hydrofining at a temperature between 500 and 800 F. in the presence of the spent reforming catalyst prior to the regeneration of said catalyst and recovering from the products of this second treatment afraction boiling in the range of a motor fuel.

2. Process according to claim 1 in which the catalyst is used in stationary form.

3. Process according to claim 1 in which the catalyst is used in finely divided form suspended in the reacting materials.

4. An improved method for preparing a fin ished motor fuel of high octane number which comprises subjecting a hydrocarbon oil consisting essentially of hydrocarbons boiling in the gasoline range to catalytic reforming in the presence of hydrogen under conditions such that there is a substantial net production of free hydrogen in the reaction and in the presence of a catalyst which gradually loses its reforming activity but is capable of being regenerated in a first reaction zone, then subjecting the products of this treatment to catalytic hydrofining at a temperature between 500 and 800 F. in a second reaction zone which contains the same type of catalyst as the first reaction zone but which has previously been used for catalytic reforming in the presence of hydrogen but has lost its activity therefor and has not yet been regenerated, and recovering from the products leaving the second reaction zone a fraction boiling in the range of a motor fuel.

5. An improved method for preparing a finished motor fuel of high octane number from a hydrocarbon oil consisting essentially of hydrocarbons boiling in the gasoline range by catalytic reforming in the presence of hydrogen under conditions such that there is a substantial net production of free hydrogen in the reaction and catalytic hydrofining which comprises introducing said oil into one of three reaction zones all of which contain the same type of reforming catalyst, which catalyst gradually loses its reforming activity but is capable of being regenerated, the said reaction zone into which the oil is introduced containing fresh or freshly regenerated catalyst, passing the products from this reaction zone into a second of said three reaction zones which contains catalyst which has already been used for catalytic reforming in the presence of hydrogen but has lost its activity therefor and has not yet been regenerated, maintaining said second of the three reaction zones under conditions which promote catalytic hydrofining, recovering a fraction boiling in the range of a motor fuel from the products leaving the said second of the three reaction zones, and mean-' while subjecting the catalyst in the third of the three reaction zones, which catalyst has already been used for catalytic reforming in the presence of hydrogen and for catalytic hydrofining, to regeneration in situ.

6. Process according to claim 5 in which the fresh oil is introduced into the first of the said three reaction zones until the catalyst in said reaction zone has lost its activity to such an extent that there ceases to be a net production of freehydrogen in the reaction sufficient to compensate for the hydrogen consumed in the subsequent catalytic hydrofining step, and the fresh oil is then introduced into the reaction zone in which the catalyst meanwhile had been undergoing regeneration.

7. A continuous process for preparing a finished motor fuel of high octane number from a hydrocarbon oil consisting essentially of hydrocarbons boiling in the gasoline range by catalytic reforming in the presence of hydrogen under conditions such that there is a substantial net production of free hydrogen in the reaction and catalytic hydrofining of the products thereof, which comprises providing four reaction zones each containing the same type of reforming catalyst which catalyst gradually loses its reforming activity but is capable of being regenerated, introducing said oil into those two of the said four reaction zones which contain the most recently. regenerated catalyst, passing the products from said two zones into a third of the said four reaction zones which contains catalyst which has already become spent for catalytic reforming in the presence of hydrogen but has not yet been regenerated, maintaining said third of the four reaction zones under conditions to promote catalytic hydrofining, recovering from the products leaving said third of the four reaction zones :3.

fraction boiling in the range of a motor fuel, and meanwhile subjecting the catalyst in the fourth of said four reaction zones, which catalyst has previously been used for both catalytic reforming in the presence of hydrogen and for catalytic hydrofining, to regeneration in situ. 

